Thin, flexible sanitary napkin

ABSTRACT

In accordance with the present invention, a sanitary napkin having a body surface and a garment surface and being comprised of an absorbent means underlayed by a liquid barrier means, wherein the sanitary napkin is relatively highly flexible and has a capacity great enough to handle medium to high menstrual flows, is provided. In a preferred embodiment, the sanitary napkin comprises, from the body surface down, an apertured formed film topsheet, an apertured nonwoven wipe acquisition sheet, a wet-laid tissue, a superabsorbent core, and a barrier sheet. Preferably, the central width of the absorbents is at least about 6.5 centimeters and the caliper of the napkin as a whole is less than about 2.6 millimeters. In a preferred embodiment, the napkin has laterally extending flaps which drape over the edges of the wearer&#39;s panties in the crotch and are attachable to the garment side of the wearer&#39;s panties.

This is a continuation of application Ser. No. 07/688,755, filed on Apr.22, 1991 now abandoned, which is a continuation of Ser. No. 07/293,606now U.S. Pat. No. 4,950,264 which is a continuation-in-part of Ser. No.07/175,559 filed Mar. 31, 1988, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to female sanitary napkins. Particularly,the present invention concerns thin, flexible sanitary napkins offeringenhanced fit and comfort through a construction which promotes acontinuously self-conforming anatomical cooperation of the sanitarynapkin to the wearer to yield a highly effective absorbent device.

2. BACKGROUND ART

All manner and variety of absorbent articles configured for theabsorption of body fluids such as menses, urine and feces are, ofcourse, well known. With respect to feminine protection devices, the arthas offered two basic types; sanitary napkins have been developed forexternal wear about the pudendal region while tampons have beendeveloped for internal wear within the vaginal cavity for interruptionof menstrual flow therefrom. Such tampon devices are disclosed in U.S.Pat. No. 4,412,833, entitled "Tampon Applicator", which patent issued toWeigner et al. on Nov. 1, 1983, and U.S. Pat. No. 4,413,986, entitled"Tampon Assembly With Means For Sterile Insertion", which patent issuedto Jacobs on Nov. 8, 1983.

Hybrid devices which attempt to merge the structural features of thesanitary napkins and the tampons into a single device have also beenproposed. Such hybrid devices are disclosed in U.S. Pat. No. 2,092,346,entitled "Catamenial Pad", which patent issued to Arone on Sep. 7, 1937,and U.S. Pat. No. 3,905,372, entitled "Feminine Hygiene ProtectiveShield", which patent issued to Denkinger on Sep. 16, 1975. Other lessintrusive hybrid devices are known as labial or interlabial sanitarynapkins and are characterized by having a portion which at leastpartially resides within the wearer's vestibule and a portion which atleast partially resides external of the wearer's vestibule. Such devicesare disclosed in U.S. Pat. No. 2,662,527, entitled "Sanitary Pad", whichpatent issued to Jacks on Dec. 15, 1953, and U.S. Pat. No. 4,631,062,entitled "Labial Sanitary Pad", which patent issued to Lassen et al. onDec. 23, 1986.

With respect to sanitary napkins, at least two general classes pertinentto the present invention exist. One such class is for the absorption ofmedium to high menstrual flows. These sanitary napkins offer a fairlyhigh absorptive capacity. Absorptive capacity is commonly achieved byproviding the napkin with a fairly thick and bulky absorbent member,commonly fluff pulp. Sanitary napkins of this class are disclosed inU.S. Pat. No. 3,294,091, entitled "Sanitary Napkin", which patent issuedto Morse on Dec. 27, 1966, U.S. Pat. No. 4,654,040, entitled"Smooth-Edged Contoured Sanitary Napkin", which patent issued to Lucerion Mar. 31, 1987, and U.S. Pat. No. 4,687,478, entitled "Sanitary NapkinWith Flaps", which patent issued to Van Tilburg on Aug. 18, 1987. Suchsanitary napkins theoretically have a high absorptive capacity, however,when the sanitary napkin is worn and subjected to the compressive forcesof the wearer's thighs and pudendal region, the fluff pulp core simplycompacts or bunches into an arbitrary, but generally rope-like shape.Such napkins commonly shift from their original placement so that afteronly a short wearing time, the napkin might only partially, if at all,be beneath the wearer's vaginal orifice or vestibule. Thus, in use,these sanitary napkins sometimes offer very little absorption. Further,the rolling and twisting of these napkins may create soiling on thewearer's panties and skin surfaces. In addition, the bulkiness of thesenapkins causes a high degree of wearing awareness and may make themquite obtrusive when worn with tight fitting slacks, body suits orbathing suits.

A second class of sanitary napkins are intended for light or lowmenstrual flows and are commonly referred to as panty liners or pantyshields. Sanitary napkins of this type are disclosed in U.S. Pat. No.4,681,578, entitled "Pantiliner With Ventilation Areas", which patentissued to Anderson and Brandt on Jul. 21, 1987. Sanitary napkins of thisclass, as a group , are thinner, somewhat more flexible and generallymore comfortable than those of the first class, however, they lack theabsorptive capacity of the napkins of the first class.

Therefore, there exists a real consumer need for a sanitary napkin whichis thin and flexible, thereby offering enhanced fit and comfort, yethaving a fluid capacity great enough for use with medium to highmenstrual flows thereby allaying consumer fears of leakage and staining.

Therefore, it is an object of the present invention to provide asanitary napkin which is thin and flexible and which is absorbent enoughto absorb and contain medium to high menstrual flows.

It is an additional object of the present invention to provide asanitary napkin which will closely conform to the various anatomicalshapes of the female urogenital and buttocks region.

It is an additional object of the present invention to provide asanitary napkin which offers enhanced fit and comfort and a low degreeof wearing awareness.

It is an additional object of the present invention to provide a thinand flexible sanitary napkin having laterally extending flaps configuredto drape over the side edges of the wearer's panties in the crotchportion thus being disposed between the side edges of the wearer'spanties in the crotch portion and the wearer's thighs.

It is an additional object of the present invention to provide thelaterally extending flaps with an attachment means on their garmentfacing surface so that the flaps can wrap around the side edges of thewearer's panties in the crotch portion and be attached to the garmentfacing side of the wearer's panties in order to provide protection fromsoiling and so as to keep the napkin properly positioned in the wearer'spanties.

These and other objects of the present invention will be more readilyapparent when considered in reference to the following description andwhen taken in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

In accordance with the present invention, a sanitary napkin having abody surface and a garment surface and being comprised of an absorbentmeans underlayed by a liquid barrier means, wherein the sanitary napkinis relatively highly flexible and has a capacity great enough to handlemedium to high menstrual flows, is provided. In a preferred embodiment,the sanitary napkin comprises, from the body surface down, an aperturedformed film topsheet, an apertured nonwoven wipe acquisition sheet, awet-laid tissue, a superabsorbent core, and a barrier sheet. Preferably,the central width of the absorbents is at least about 7.0 centimetersand the caliper of the napkin as a whole is less than about 2.5millimeters. In a preferred embodiment, the napkin has laterallyextending flaps which drape over the edges of the wearer's panties inthe crotch and are attachable to the garment side of the wearer'spanties.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a preferred sanitary napkin embodiment ofthe present invention with portions being torn away to show underlyingstructure.

FIG. 2 is a lateral cross-sectional view of the preferred sanitarynapkin embodiment shown in FIG. 1 taken along line 2--2 of FIG. 1.

FIG. 3 is a top plan view of a preferred topsheet and wipe acquisitionsheet laminate with portions of the topsheet being torn away to showunderlying structure.

FIG. 4 is a top plan view of an alternatively preferred sanitary napkinembodiment of the present invention with portions being torn away toshow underlying structure.

FIG. 5 is a top plan view of another alternatively preferred sanitarynapkin embodiment of the present invention with portions being torn awayto show underlying structure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention relates to female sanitary napkins and inparticular to sanitary napkins which are thin and flexible and offerenhanced fit, comfort, and containment.

As used herein, the term "sanitary napkin" refers to an article which isworn by females adjacent to the pudendal region and which is intended toabsorb and contain the various exudates which are discharged from thebody (e.g., blood, menses and urine) and which is intended to bediscarded after a single use (i.e., it is not intended to be launderedor otherwise restored or reused). Interlabial devices which residepartially within and partially external of the wearer's vestibule arealso within the scope of this invention. As used herein, the term"pudendal" refers to the externally visible female genitalia and islimited to the labia majora, the labia minora, the clitoris, and thevestibule.

A preferred embodiment of a sanitary napkin 10 of the present inventionis shown in FIGS. 1 and 2. As can be seen in FIGS. 1 and 2, a preferredsanitary napkin 10 basically comprises an absorbent means 13 and aliquid impermeable barrier means 16. The absorbent means 13 may be anymeans which is generally compressible, conformable, non-irritating tothe wearer's skin and capable of absorbing and containing body exudatessuch as menses, blood and urine. Preferably, the absorbent means 13maintains integrity when wetted, in use. The absorbent means 13 has afirst major surface 19 and a second major surface 22. The barrier means16 is adjacent the second major surface 22 of the absorbent means 13.The barrier means 16 may be any means which is flexible and liquidimpervious and which prevents the exudates absorbed and contained in theabsorbent means 13 from wetting articles which contact the sanitarynapkin 10 such as panties.

In the preferred embodiment shown in FIGS. 1 and 2, the absorbent means13 is comprised of a liquid permeable topsheet 25, a liquid permeablewipe acquisition sheet 28, a wet-laid tissue sheet 31 and an absorbentcore 34. In the preferred embodiment shown in FIGS. 1 and 2, the barriermeans 16 is a barrier sheet. The absorbent core 34 is comprised ofhydrogel-forming material 37 disposed between two air-laid tissue sheets40 and 43. The sanitary napkin 10 has side edges 11 and end edges 12which together form the periphery 15 of the sanitary napkin 10. Thesanitary napkin 10 has a body surface 26 which is generally defined bythe topsheet 25 and a garment surface 17 which is generally defined bythe barrier sheet 16.

Looking at some of the elements of the sanitary napkin 10 morespecifically, the absorbent core 34 may be any means which is generallycompressible, conformable, non-irritating to the wearer's skin andcapable of absorbing and containing body exudates. The absorbent core 34has a first major surface 46, a second major surface 49, a pair of endedges 52 and a pair of side edges 55. The absorbent core 34 may bemanufactured in a wide variety of sizes and shapes (e.g., rectangular,hourglass, etc.). A preferred shape of the absorbent core 34 is thedogbone shape shown in FIG. 1. This preferred absorbent core 34 is about22.0 centimeters long (longitudinal dimension along the longitudinalcenterline 58), about 7.0 centimeters wide across its midportion(lateral dimension along the lateral centerline 61) and about 8.0centimeters wide across its widest portion (lateral dimension). Theabsorbent core 34 is symmetrically configured for ease of manufactureand so that no conscious effort is required by the wearer to properlyplace the napkin 10 in the direction it should be worn. The midportionis configured to basically conform to the wearer's thighs and to thethinner crotch portion of the wearer's panties so as to preventexcessive bunching. The size of the absorbent core 34 may be varied toaccommodate wearers ranging in size and also ranging in the expectedamount of exudate fluid volume. The absorbent core 34 may be attachedover the core's first or second major surfaces 46 and 49, respectively,to adjacent members such as the topsheet 25 and barrier sheet 16 by anyof the means well known in the art, such as by spray-gluing or lines orspots of adhesive. Such attachment facilitates integrity andrecoverability of the absorbent materials in use so as to maintain anoptimum degree of absorbency. Preferably, the absorbent core 34 has awet-tensile strength in the cross-direction of at least about 100.0grams per centimeter. Wet tensile strength is determinable by ASTMStandard D 829-49.

The absorbent core 34 may be manufactured from a wide variety of liquidabsorbent materials commonly used in disposable sanitary napkins,diapers, and other absorbent articles. Examples of suitable absorbentmaterials include comminuted wood pulp which is generally referred to asairfelt, creped cellulose wadding, absorbent foams, absorbent sponges,synthetic staple fibers, polymeric fibers, hydrogel-forming polymergelling agents, or any equivalent materials or combinations ofmaterials. A particularly preferred absorbent material are polymericgelling agents. Polymeric gelling agents are those materials which, uponcontact with fluids (i.e., liquids) such as water or body fluids, imbibesuch fluids and thereby form hydrogels. In this manner, fluid dischargedinto the absorbent core 34 can be acquired and held by the polymericgelling agent, thereby providing the articles herein with enhancedabsorbent capacity and/or improved fluid retention performance.

The polymeric gelling agent which is employed in the absorbent core 34will generally comprise particles of a substantially water-insoluble,slightly cross-linked, partially neutralized, hydrogel-forming polymermaterial. Such polymer materials can be prepared from polymerizable,unsaturated, acid-containing monomers. Suitable unsaturated acidicmonomers for use in preparing the polymeric gelling agents used in thisinvention include those listed in U.S. Pat. No. 4,654,039, entitled"Hydrogel-Forming Polymer Compositions For Use In Absorbent Structures",which issued to Brandt, Goldman and Inglin on Mar. 31, 1987, and whichpatent is incorporated herein by reference. Preferred monomers includeacrylic acid, methacrylic acid, and 2-acrylamido-2-methyl propanesulfonic acid. Acrylic acid itself is especially preferred forpreparation of the polymeric gelling agent material.

In the hydrogel-forming polymeric gelling agent the polymeric componentformed from unsaturated, acid-containing monomers may be grafted ontoother types of polymer moieties such as starch or cellulose.Polyacrylate grafted starch materials of this type are especiallypreferred for use herein.

Preferred polymer gelling agents which can be prepared from conventionaltypes of monomers include hydrolyzed acrylonitrile grafted starch,polyacrylate grafted starch, polyacrylates, maleic anhydride-basedcopolymers and combinations thereof. Especially preferred are thepolyacrylates and polyacrylate grafted starch.

Whatever the nature of the basic polymer components of thehydrogel-forming polymeric gelling agents used in the absorbent core 34herein, such materials will in general be slightly cross-linked.Cross-linking serves to render the hydrogel-forming polymer gellingagents used in this invention substantially water-insoluble, andcross-linking thus in part determines the gel volume and extractablepolymer characteristics of the hydrogels formed from the polymericgelling agents employed. Suitable cross-linking agents are well known inthe art and include, for example, those described in greater detail inU.S. Pat. No. 4,076,663, which patent issued to Masuda et al. on Feb.28, 1978, and which patent is incorporated herein by reference.Preferred cross-linking agents are the di- or polyesters of unsaturatedmono- or polycarboxylic acids with polyols, the bisacrylamides and thedi- or triallyl amines. Especially preferred cross-linking agents areN,N'-methylenebisacrylamide, trimethylol propane triacrylate andtriallyl amine. The cross-linking agent can generally comprise fromabout 0.001 mole percent to 5.0 mole percent of the resultinghydrogel-forming polymer material. More preferably, the cross-linkingagent will comprise from about 0.01 mole percent to 3.0 mole percent ofthe hydrogel-forming polymeric gelling agent used herein.

The slightly cross-linked, hydrogel-forming polymeric gelling agentswhich may be used in the articles of the present invention are generallyemployed in their partially neutralized form. For purposes of thisinvention, such materials are considered partially neutralized when atleast 25.0 mole percent, and preferably at least 50.0 mole percent ofmonomers used to form the polymer are acid group-containing monomerswhich have been neutralized with a salt-forming cation. Suitablesalt-forming cations include alkali metal, ammonium, substitutedammonium, and amines. This percentage of the total monomer utilizedwhich are neutralized acid group-containing monomers is referred toherein as the "degree of neutralization."

The polymeric gelling agent materials used in the absorbent articlesherein must have a relatively high capacity for imbibing fluidsencountered in such articles. The absorbent capacity of these materialscan be quantified by referencing the "gel volume" of the polymericgelling agents which are to be selected for use in the presentinvention.

For purposes of this invention, gel volume can be defined in terms ofthe amount of synthetic urine absorbed by any given polymeric gellingagent and is specified as grams of synthetic urine per gram of polymericgelling agent. Gel volume in synthetic urine can be determined byforming a suspension of about 0.1-0.2 parts of dried polymeric gellingagent to be tested with about 20 parts of synthetic urine. Thissuspension is maintained at ambient temperature under gentle stirringfor a time sufficient, e.g., about 1 hour, for swelling equilibrium tobe attained. The gel volume of the polymeric gelling agent in grams ofsynthetic urine per gram of polymeric gelling agent is then calculatedfrom the weight fraction of the polymeric gelling agent in thesuspension and the ratio of the liquid volume excluded from the formedhydrogel to the total volume of the suspension.

The gel volume of the gelling agents used in the absorbent core 34herein will generally be at least about 20.0 grams of synthetic urineper gram of polymeric gelling agent. More preferably, the gel volume ofthe materials employed will range from about 20.0 to about 60.0, mostpreferably from about 22.0 to about 35.0 grams of synthetic urine pergram of polymeric gelling agent.

Within the webs which form the layers of the absorbent core 34, theparticles of the polymeric gelling agent should be thoroughly dispersedbut may or may not be uniformly distributed. In particular, there may beregions or zones of the core layers which have higher concentrations ofgelling agent particles than do other regions or zones of the layers.

In a preferred embodiment, the sanitary napkin 10 of the presentinvention will have a hydrogel-forming polymeric gelling agentdistributed throughout at least about 17.0 square centimeters of thenapkin, more preferably throughout at least about 50.0 squarecentimeters of the napkin, and most preferably throughout at least about100.0 square centimeters of the napkin. Preferably, the hydrogel-formingpolymeric gelling agent will be distributed in an amount of from about0.001 grams per square centimeter to about 0.009 grams per squarecentimeter, more preferably of from about 0.003 grams per squarecentimeter to about 0.008 grams per square centimeter, and mostpreferably from about 0.004 grams per square centimeter to about 0.007grams per square centimeter. Preferably, the absorbent core 34 willcontain from about 5.0% to about 85.0% by weight of hydrogel-formingpolymeric gelling agent, more preferably from about 10.0% to about70.0%, and most preferably from about 15.0% to about 55.0%.

In the preferred embodiment shown in FIG. 2, the absorbent core 34 is alaminate comprised of a layer of superabsorbent polymer material 37disposed between two air-laid tissues 40 and 43. A suitable laminate isthe superabsorbent laminate WATER-LOCK L-535 available from the GrainProcessing Corporation of Muscatine, Iowa (WATER-LOCK registered TM byGrain Processing Corporation). Such superabsorbent laminates aredisclosed in U.S. Pat. No. 4,467,012, entitled "Composition ForAbsorbent Film And Method Of Preparation", which patent issued toPedersen et al. on Aug. 21, 1984, and U.S. Pat. No. 4,260,443, entitled"Laminated Absorbent Process", which patent issued to Lindsay et al. onApr. 7, 1981, and which patents are incorporated herein by reference.The WATER-LOCK L-535 has a hydrogel polymer loading of 0.005 grams persquare centimeter, however, loadings of 0.001-0.009 grams per squarecentimeter have been found acceptable. The first and second tissuelayers 40 and 43 provide containment of the superabsorbent polymermaterial 37, improve lateral wicking of the absorbed exudates throughoutthe absorbent core 34 and provide a degree of absorbency. In the case ofnon-particulate hydrogel-forming polymer gelling agents which can beformed into fibrous sheets, foams or films, the non-particulate gellingagent may comprise from about 15% to about 100% by weight of theabsorbent core 34, more preferably of from about 40% to about 100%, andmost preferably of from about 60% to about 100%. The basis weight ofsuch non-particulate superabsorbents may be from about 0.002 to about0.028 grams per square centimeter, more preferably of from about 0.003to about 0.018, and most preferably of from about 0.004 to about 0.010.Two suitable and commercially available non-particulate absorbentmaterials for the absorbent core 34 are a double layer acrylic fibrousmaterial available under the tradename Lanseal F from the Choli Company,LTD., of Higashi, Osaka Japan and a carboxymethylcellulose fibrousmaterial available under the tradename Aqualon C from Hercules, Inc. ofWilmington, Del.

The total absorbent capacity of the absorbent core 34 should becompatible with the design exudate loading for the intended use of thesanitary napkin 10. Further, the absorbent capacity of the absorbentcore 34 may be varied to accommodate wearers ranging in the expectedamount of exudate fluid volume. For instance, a different absorbentcapacity may be utilized for sanitary napkins intended for daytime useas compared with those intended for nighttime use, or for sanitarynapkins intended for use by teenage females as compared with thoseintended for use by more mature women.

It should be noted that the scope of the present invention is notintended to extend to sanitary napkins which are void of anysuperabsorbent material and which have a central absorbent memberoverlayed solely by nonwoven materials, wherein the nonwoven materialshave caliper of less than 0.50 millimeters, as determined by the calipertest, as later defined.

Superimposed over the absorbent core 34 and extending about 3.0millimeters beyond the edges 52 and 55 of the absorbent core 34 is thewet-laid tissue 31. The wet-laid tissue 31 is liquid permeable. Asatisfactory wet-laid tissue 31 has a basis weight of about 15.8 gramsper square meter and an air permeability of about 30.5 cubic meters perminute per square meter at a pressure differential of about 12.8millimeters of water. Preferably, the wet-laid tissue 31 maintainsintegrity when wetted, in use. The wet-laid tissue 31 preferably has awet tensile strength in the cross-direction of at least about 15.0 gramsper centimeter. Suitable tissues 31 and their manufacture are disclosedin U.S. Pat. No. 3,301,746, entitled "Process For Forming AbsorbentPaper By Imprinting A Fabric Knuckle Pattern Thereon Prior To Drying AndPaper Thereof", which patent issued to Sanford and Sisson on Jan. 31,1967, and which patent is incorporated herein by reference. In apreferred embodiment, those parts of the wet-laid tissue 31 which extendbeyond the edges 52 and 55 of the absorbent core 34 are associated withthe barrier sheet 16. The wet-laid tissue 31 may be associated with thebarrier sheet 16 by attachment means as are well known in the art suchas by spray-gluing or lines or spots of adhesive. The wet-laid tissue 16serves a number of purposes. The tissue 31 serves to confine any loosesuperabsorbent material 37 between the tissue 31 and the barrier sheet16 thereby preventing the superabsorbent material 37 from coming incontact with the wearer's skin. Also, the tissue 31 improves lateralwicking of the absorbed exudates over the absorbent core 34 therebyproviding a more even distribution of the exudates throughout theabsorbent core 34. Further, the tissue 31 provides some degree ofabsorbency and further inhibits exudates which have reached and beenabsorbed by the absorbent core 34 from rewetting the wearer's skin.

Superimposed over the wet-laid tissue 31 is a liquid permeable wipeacquisition sheet 28. In a preferred embodiment, the wipe acquisitionsheet 28 is a nonwoven sheet. In the preferred embodiment shown in FIG.2, the sheet 28 is a spunlaced 70%/30% rayon/polyester fiber sheet.Spunlaced fabrics of this type are manufactured by E. I. DuPont Nemours& Company of Wilmington, Del., and are made available under thetradename "SONTARA" (SONTARA registered TM by E. I. DuPont Nemours &Company). These fabrics are available in a number of suitable styles,however, Style 8407 in its apertured form, having a basis weight of0.005 grams per square centimeter and a thickness of about 0.04millimeters, is preferred. The wipe acquisition sheet 28 extends beyondthe edges of the wet-laid tissue 31 where it too is associated with thebarrier sheet 16. The wipe acquisition sheet 28 greatly improves lateralwicking of exudates over the absorbent core 34 thereby providing a moreeven distribution of the exudates throughout the absorbent core 34. Thelateral wicking of the wipe acquisition sheet 28 is important for thefollowing reason. Many bulky prior art sanitary napkins rely on a highdegree of vertical absorption at the point where exudates are initiallydeposited. In other words, because the absorbent cores of these napkinsare fairly thick, they can absorb a high degree of exudates throughouttheir thickness while utilizing only a small degree of their surfacearea or lateral absorption capability. However, the relatively thinnapkins 10 of the present invention have a comparatively small degree ofvertical absorption. Therefore, for a relatively large amount ofexudates to be absorbed, a wipe acquisition sheet 28 which can laterallydisperse the exudates over a large surface area of the absorbent core 34where the exudates can better and faster be vertically absorbed ishighly desirable. Further, the wipe acquisition sheet 28 provides afairly high degree of initial absorption during the time intervalbetween the time exudates are deposited onto the topsheet 25 and thetime they are absorbed by the absorbent core 34. This property will bemore specifically described later.

Superimposed over the wipe acquisition sheet 28 is the liquid permeabletopsheet 25. In a preferred embodiment, the topsheet 25 is associatedwith the wipe acquisition sheet 28 by spray-gluing the topsheet 25 tothe surface of the wipe acquisition sheet 28. The topsheet 25 iscompliant, soft feeling, and non-irritating to the wearer's skin.Further, the topsheet 25 is liquid previous, permitting liquid toreadily transfer through its thickness. A suitable topsheet 25 may bemanufactured from a wide range of materials such as polymeric materials,formed thermoplastic films, apertured plastic films, porous foams,reticulated foams, natural fibers (e.g., wood or cotton fibers),synthetic fibers (e.g., polyester or polypropylene fibers) or from acombination of natural and synthetic fibers, with apertured formed filmsbeing preferred. Formed films are preferred for the topsheet 25 becausethey are pervious to liquids and yet non-absorbent. Thus, the surface ofthe formed film which is in contact with the body remains dry, therebyreducing body soiling and creating a more comfortable feel for thewearer. Suitable formed films are described in U.S. Pat. No. 3,929,135,entitled "Absorptive Structure Having Tapered Capillaries", which patentissued to Thompson on Dec. 30, 1975, U.S. Pat. No. 4,324,246, entitled"Disposable Absorbent Article Having A Stain Resistant Topsheet", whichpatent issued to Mullane and Smith on Apr. 13, 1982, U.S. Pat. No.4,342,314, entitled "Resilient Plastic Web Exhibiting Fiber-LikeProperties", which patent issued to Radel and Thompson on Aug. 3, 1982,and U.S. Pat. No. 4,463,045, entitled "Macroscopically ExpandedThree-Dimensional Plastic Web Exhibiting Non-Glossy Visible Surface andCloth-Like Tactile Impression", which patent issued to Ahr, Louis,Mullane, and Ouellete on Jul. 31, 1984, all of which patents areincorporated herein by reference.

In a preferred embodiment of the present invention, the body surface 26of the topsheet 25 is hydrophilic. The hydrophilic body surface 26 helpsliquid to transfer through the topsheet 25 faster than if the bodysurface 26 was not hydrophilic. This diminishes the likelihood thatmenstrual fluid will flow off the topsheet 25 rather than being absorbedby the absorbent core 34. In a preferred embodiment, the body surface 26of the topsheet 25 is made hydrophilic by treating the body surface 26with a surfactant. It is preferred that the surfactant be substantiallyevenly and completely distributed throughout the body surface 26 of thetopsheet 25. This can be accomplished by any of the common techniqueswell known to those skilled in the art. For example, the surfactant canbe applied to the topsheet 25 by spraying, by padding, or by the use oftransfer rolls. Further, the surfactant can be incorporated into thepolymeric materials of a formed film topsheet or between or within thefibers of a nonwoven topsheet.

The barrier means 16 is adjacent the second major surface 22 of theabsorbent means 13. In a preferred embodiment, the absorbent means 13may be affixed over the second major surface 22 of the absorbent means13 to the barrier means 16. Any of the common techniques well known inthe art, such as spray-gluing or lines or spots of adhesive may be usedfor this purpose. The barrier means 16 generally defines the garmentsurface 17 of the sanitary napkin 10. The barrier means 16 may be anymeans which is impervious to liquids and which prevents exudatesabsorbed and contained in the absorbent means 13 from soiling articles,such as panties, which come in contact with the garment surface 17 ofthe sanitary napkin 10. In the preferred embodiment of the sanitarynapkin 10 illustrated in FIGS. 1 and 2, the barrier means 16 is abarrier sheet manufactured from a thin plastic film. Other flexibleliquid impervious materials may also be used. Preferably, the barriersheet 16 is a polyethylene film having a thickness of from about 0.012millimeter to about 0.051 millimeter. As used herein, the term"flexible" refers to materials which are compliant and which willreadily conform to the general shape and contours of the human body.

A suitable polyethylene film is manufactured by Monsanto ChemicalCorporation and marketed in the trade as Film No. 8020. The barriersheet 16 is preferably embossed and/or matte finished to provide a moreclothlike appearance. Further, the barrier sheet 16 may permit vapors toescape from the absorbent means 13 while still preventing exudates frompassing through the barrier sheet 16.

Preferably, the topsheet 25 and the barrier sheet 16 have length andwidth dimensions generally larger than the absorbent core 34 so thatthey extend beyond the edges 52 and 55 of the absorbent core 34 wherethey are associated together in a suitable manner. As used herein, theterm "associated" encompasses configurations whereby a first member isdirectly joined to a second member and configurations whereby a firstmember is indirectly joined to a second member by affixing the firstmember to intermediate members which in turn are affixed to the secondmember. The extension of the topsheet 25 and/or the barrier sheet 16beyond the core end edges 52 and the core side edges 55 of the absorbentcore 34 form the end edges 11 and the side edges 12, respectively, ofthe sanitary napkin 10. In a preferred embodiment, the barrier sheet 16and the topsheet 25 have an elliptical shape and extend beyond theabsorbent core 34 a distance of at least about 1.0 centimeter where theyare joined directly to each other by attachment means as are well knownin the art. The attachment means may be, for example, a uniformcontinuous layer of adhesive a patterned layer of adhesive, or an arrayof separate lines or spots of adhesives.

The sanitary napkin 10 of the present invention has a lowflexure-resistance. Thus, the sanitary napkin 10 of the presentinvention is highly flexible and conforms very well to the variousshapes of the female urogenital region. Preferably, the sanitary napkin10 of the present invention has a flexure-resistance of less than about250.0 grams, more preferably less than about 175.0 grams and mostpreferably less than about 130.0 grams.

The flexure-resistance of a sanitary napkin is measured by peak bendingstiffness. Peak bending stiffness is determined by a test which ismodeled after the ASTM D 4032-82 CIRCULAR BEND PROCEDURE, the procedurebeing considerably modified and performed as follows. The CIRCULAR BENDPROCEDURE is a simultaneous multi-directional deformation of a materialin which one face of a specimen becomes concave and the other facebecomes convex. The CIRCULAR BEND PROCEDURE gives a force value relatedto flexure-resistance, simultaneously averaging stiffness in alldirections.

APPARATUS

The apparatus necessary for the CIRCULAR BEND PROCEDURE is a modifiedCircular Bend Stiffness Tester, having the following parts:

A smooth-polished steel plate platform which is 102.0×102.0×6.35millimeters having an 18.75 millimeter diameter orifice. The lap edge ofthe orifice should be at a 45 degree angle to a depth of 4.75millimeters.

A plunger having an overall length of 72.2 millimeters, a diameter of6.25 millimeters, a ball nose having a radius of 2.97 millimeters and aneedle-point extending 0.88 millimeter therefrom having a 0.33millimeter base diameter and a point having a radius of less than 0.5millimeter, the plunger being mounted concentric with the orifice andhaving equal clearance on all sides. Note that the needle-point ismerely to prevent lateral movement of the test specimen during testing.Therefore, if the needle-point significantly adversely affects the testspecimen (for example, punctures an inflatable structure), than theneedle-point should not be used. The bottom of the plunger should be setwell above the top of the orifice plate. From this position, thedownward stroke of the ball nose is to the exact bottom of the plateorifice.

A force-measurement gauge and more specifically an Instron invertedcompression load cell. The load cell has a load range of from about 0.0to about 2000.0 grams.

An actuator, and more specifically the Instron Model No. 1122 having aninverted compression load cell. The Instron 1122 is made by the InstronEngineering Corporation, Canton, Mass.

NUMBER AND PREPARATION OF SPECIMENS

In order to perform the procedure for this test, as explained below,five representative sanitary napkins are necessary. From one of the fivenapkins to be tested, some number "Y" of 37.5×37.5 millimeter testspecimens are cut. Specimens having portions in which a topsheet isjoined directly to a barrier sheet or which are a laminate of atopsheet, two or less tissue sheets and a barrier sheet, should not betested. The reason that these specimens are not tested is due to therealization that prior art napkins exist in which a topsheet is joinedto a barrier sheet beyond the edges of an absorbent core in theperiphery of the napkin, such portions of which are highly flexible.However, the present invention is more concerned with the overallflexibility of the sanitary napkin and not merely the peripheralportions thereof and, therefore, the flexibility of the presentinvention is more concerned with the flexibility of the significantabsorbent portions of the sanitary napkin. If any of these significantabsorbent portions of the sanitary napkin meet the parameters of thistest, then the sanitary napkin satisfies the test. Therefore, a numberof different specimens should be tested from each sanitary napkin.Certainly, the structurally most flexible portion of the sanitary napkinshould be tested, excluding those portions excluded above. The testspecimens should not be folded or bent by the test person, and thehandling of specimens must be kept to a minimum and to the edges toavoid affecting flexural-resistance properties. From the four remainingsanitary napkins, an equal number "Y" of 37.5×37.5 millimeter specimens,identical to the specimens cut from the first napkin, are cut. Thus, thetest person should have "Y" number of sets of five identical specimens.

PROCEDURE

The procedure for the CIRCULAR BEND PROCEDURE is as follows. Thespecimens are conditioned by leaving them in a room which is 21°±1° C.and 50±2% relative humidity for a period of two hours. The test plate isleveled. The plunger speed is set at 50.0 centimeters per minute perfull stroke length. A specimen is centered on the orifice platform belowthe plunger such that the body surface 26 of the specimen is facing theplunger and the garment surface 17 of the specimen is facing theplatform. The indicator zero is checked and adjusted, if necessary. Theplunger is actuated. Touching the specimen during the testing should beavoided. The maximum force reading to the nearest gram is recorded. Theabove steps are repeated until all five of the identical specimens havebeen tested.

CALCULATIONS

The peak bending stiffness for each specimen is the maximum forcereading for that specimen. Remember that "Y" number of sets of fiveidentical specimens were cut. Each set of five identical specimens istested and the five values received for that set are averaged. Thus, thetest person now has an average value for each of the "Y" sets tested.Remember, if any of the significantly absorbent portions of the sanitarynapkin have the requisite flexure-resistance, then the napkin satisfiesthe parameters of this test. Therefore, the flexure-resistance for aparticularly designed sanitary napkin is the greatest of these averagepeak bending stiffnesses.

As alluded to earlier, the combination of topsheet 25 and wipeacquisition sheet 28 imparts some beneficial properties to the sanitarynapkin 10. In particular, the combination of an apertured formed filmtopsheet 25 superimposed over an apertured nonwoven wipe acquisitionsheet 28 is beneficial. A preferred wipe acquisition sheet 28 is thepreviously described SONTARA 8407. An enlarged depiction of such anarrangement is shown in FIG. 3. Such a combination is even morebeneficial when the nonwoven wipe acquisition sheet 28 is formed orpositioned such that no fiber bundles 89 of the sheet 28 are beneathsome of the apertures 83 of the formed film topsheet 25 (i.e., theapertures in the two sheets 25 and 28 are aligned) while beneath otherapertures 83 of the formed film topsheet 25 fiber bundles 89 of thenonwoven sheet 28 are present (i.e., apertures in the two sheets 25 and28 are not aligned). Such an arrangement is readily apparent in FIG. 3,wherein the apertures 86 of the nonwoven sheet 28 are larger than theapertures 83 of the formed film topsheet 25. Such an arrangementprovides the sanitary napkin 10 at least two beneficial properties:enhanced gush acquisition and enhanced wipe acquisition. Gushacquisition is enhanced in those areas where the apertures 83 of thetopsheet 25 are aligned with the apertures 86 of the nonwoven wipeacquisition sheet 28. The aligned apertures 83 and 86 provide a directroute for exudates to flow from the body surface 26 of the topsheet 25to the central absorbent materials of the napkin 10. Further, theapertures 83 and 86 themselves are able to contain a degree of fluidwithin their walls or boundaries until such fluid is absorbed. Wipeacquisition, which is the ability to pull liquid exudates from thewearer's skin into the absorbent material of the napkin 10, is enhancedin those areas where fiber bundles 89 of the nonwoven wipe acquisitionsheet 28 are aligned such that the fiber bundles 89 are beneath theopenings of the apertures 83 of the topsheet 25.

As just mentioned, wipe acquisition is critical in those regions wherethe topsheet 25 is in contact with exudates on the wearer's skin. Insuch areas, the sanitary napkin 10 is likely under compressive forcesfrom the wearer's body. When such is the case, the fiber bundles 89 ofthe nonwoven wipe acquisition sheet 28 beneath the apertures 83 of thetopsheet 25 are forced somewhat up into the apertures 83 of the topsheet25, closer to the wearer's skin. Obviously, the spaces between the fiberbundles 89 and the walls of the apertures 83 or between the fibers ofthe fiber bundles 89 themselves will be less than the spaces which werebetween only the walls of the apertures 83. These spaces arecapillaries. As is well known in the art, as capillary spaces aredecreased, capillary or drawing action is increased. Thus, the capillaryaction in these apertures 83 where fiber bundles 89 are present isincreased and the sanitary napkin 10 is better able to draw exudatesfrom the wearer's skin into these capillaries and eventually into thecentral absorbent materials of the sanitary napkin 10.

Although all of the apertures 83 of the topsheet 25 are referenced bythe numeral "83", for the following teaching purposes, specificreference is directed to the aperture of FIG. 3 specifically labeled anddesignated "83". The specific aperture 83 referenced is an example inwhich an aperture 83 of the topsheet 25 is aligned with an aperture 86of the nonwoven wipe acquisition sheet 28. Theoretically, such anaperture is useful for gush acquisition since exudates haveuninterrupted flow from the body surface 26 of the topsheet 25 to thecentral absorbent material (not shown). Next, attention is directed tothe aperture 83 immediately to the right of the specific aperture 83just referenced. As seen, this aperture 83 is superimposed over a fiberbundle 89 of the nonwoven wipe acquisition sheet 28. Theoretically,exudates that flow into the aperture 83 will enter the capillaries ofthe fiber bundle 89. The exudates will then either be pulled or absorbedinto the central absorbent materials or wicked to intersecting fiberbundles 89, then wicked further to other intersecting fiber bundles 89,and so on, until the exudates are absorbed into a more laterally distantportion of the central absorbent materials. Hence, a large portion ofthe total absorbent capacity of the absorbent materials can be utilized.

As previously mentioned, the sanitary napkin 10 of the present inventionhas a liquid capacity great enough to absorb medium to high menstrualflows. Two capacities, which, depending on the size of the sanitarynapkin may be the same, are determinable: test capacity and totalcapacity. Preferably, the napkin 10 of the present invention has a testcapacity of at least about 8.0 grams, more preferably of at least about15.0 grams, and most preferably of at least about 18.0 grams.Preferably, the napkin 10 of the present invention has a total capacityof at least about 20.0 grams, more preferably of at least about 30.0grams, and most preferably of at least about 40.0 grams.

The test and total capacities of a sanitary napkin are determined asfollows. Any panty adhesive release paper is removed from the napkin tobe tested. To determine test capacity, a 4.75×14.0 centimeters portionof the sanitary napkin is cut from the portion of the sanitary napkinwhich would be centered under the vaginal orifice when the sanitarynapkin is worn. Total capacity is determined using the entire napkinminus any release paper. The article is weighed to the nearest 0.1 gram.The article is then submerged in a beaker of sterile saline (obtainablefrom the Baxter Travenol Company of Deerfield, Ill.), such that thearticle is totally submerged and is not bent or otherwise twisted orfolded. The article is submerged for 10 minutes. The article is removedfrom the saline and suspended for two minutes in a vertical position toallow the saline to drain out of the article. The article is then placedbody facing surface down onto an absorbent blotter, such as the filterpaper #631 available from the Filtration Science Corp., Eaton-DikemanDivision of Mount Holly Springs, Pa. A uniform 17.6 grams per squarecentimeter load is placed over the article to squeeze excess fluid out.The absorbent blotter is replaced every 30 seconds until the amount offluid transferred to the absorbent blotter is less than 0.5 grams in a30 second period. Next, the article is weighed to the nearest 0.1 gramand the dry weight of the article is subtracted. The difference in gramsis the test or total capacity of the article, whichever the case may be.

The central absorbent width 63 of absorbent material of the sanitarynapkin 10 of the present invention is an important parameter. The term"central absorbent width" refers to a specific area of the sanitarynapkin 10 determinable as follows, reference being had to FIG. 5. Apoint 64 on the sanitary napkin 10 which is disposed beneath the centerof the vaginal orifice, when worn, is located. A plane 65 parallel tothe lateral centerline 61 and 3.75 centimeters forward from the point 64in the direction of the wearer's mons pubis is located. Another plane 66parallel to the lateral centerline 61 and 5.0 centimeters rearward fromthe point 64 in the direction of the wearer's buttocks is also located.The greatest flat-out, uncompressed, unmanipulated, lateral width ofabsorbent material of the sanitary napkin 10 between the planes 65 and66 is the central absorbent width 63 of the sanitary napkin 10. Itmatters not whether the absorbent material is a single sheet,overlapping sheets, staggered sheets, etc., and it matters not whetherthe absorbent material is a nonwoven sheet, an absorbent topsheet, anexample, a sanitary napkin 10 of the present invention might have a wipeacquisition sheet 28 or a wet-laid tissue 31 having a width of about7.75 centimeters and an absorbent core 34 having a width of about 3.8centimeters. Thus, in this example, the sanitary napkin 10 has a centralabsorbent width 63 of 7.75 centimeters.

The sanitary napkin 10 of the present invention must have a centralabsorbent width 63 of at least about 6.5 centimeters, more preferably ofat least about 7.0 centimeters, more preferably of at least about 7.75centimeters, and most preferably of at least about 9.0 centimeters. Thecentral absorbent width 63 of the sanitary napkin 10 of the presentinvention is believed important for the following reason. As statedpreviously, the sanitary napkin 10 of the present invention relies moreon the lateral distribution of exudates over or through a relativelylarge surface area of the absorbent core 34 rather than on a high degreeof vertical absorption common to many prior art sanitary napkins.Therefore, because exudates which are distributed onto the topsheet 25may not be quickly absorbed before they migrate across the topsheet 25,it is important to contain such exudates pending absorption. Thespecified central absorbent width 63 of the sanitary napkin 10 of thepresent invention has been determined based on the width of a flexiblenapkin which will cup around the labia in the region of the vaginalorifice such that at least the edges of the absorbent material arepositioned in the uppermost part of the wearer's legs at the crotch.Thus, the sanitary napkin 10 and the absorbent material may be cuppedshaped in the surrounding regions of the vaginal orifice and exudatesdeposited thereon will be contained until absorbed.

Because of the flexibility requirements of the sanitary napkins 10 ofthe present invention, it is likely that the sanitary napkins 10 of thepresent invention will be relatively thin. It is preferred to keep thesanitary napkins 10 of the present invention thin so that they will havea low wearing awareness and also to keep them as unobtrusive aspossible. The sanitary napkin 10 shown in FIGS. 1 and 2 has a caliper ofabout 1.9 millimeters. The caliper of a sanitary napkin 10 is determinedby the following test.

A comparator gauge, and specifically the Ames, Model 130 with dialindicator Model 482, available from the B.C. Ames, Company of Waltham,Mass. is needed. The comparator gauge should have a circular comparatorfoot made of aluminum and having a weight of 10.0 grams and a contactsurface of 5.16 square centimeters. The comparator gauge is zeroed. An80.0 grams stainless steel weight is placed on the spindle extendingabove the comparator dial. The comparator foot is raised and the napkin,with any panty adhesive release paper being removed, is placed garmentsurface down on the base plate. The napkin is positioned on the baseplate so that when the foot is lowered it is in the center of thenapkin. Try to smooth out or avoid any wrinkles in the napkin. Gentlylower the foot onto the napkin. Determine the napkin caliper by readingthe comparator dial 30 seconds after the foot comes in contact with thenapkin. Repeat the measurement 3.0 centimeters from each of the ends ofthe absorbent material along the longitudinal centerline 58 of thenapkin. The average of the three readings is the caliper of the sanitarynapkin. Preferably, the sanitary napkins 10 of the present inventionhave a caliper of less than about 2.6 millimeters, more preferably lessthan about 2.2 millimeters, and most preferably less than about 2.0millimeters.

An alternative embodiment of a sanitary napkin 10 of the presentinvention is shown in FIG. 4. In this embodiment, the sanitary napkin 10has two flaps 70 each of which are adjacent to and extend laterally froma side edge 55 of the absorbent core 34. The flaps 70 are configured todrape over the edges of the wearer's panties in the crotch region sothat the flaps 70 are disposed between the edges of the wearer's pantiesand the wearer's thighs. The flaps 70 serve at least two purposes.First, the flaps 70 help serve to prevent soiling of the wearer's bodyand panties by menstrual fluid. Second, the flaps 70 are preferablyprovided with attachment means 71 on their garment surface 17 so thatthe flaps 70 can be folded back under the panty and attached to thegarment facing side of the panty. In this way, the flaps 70 serve tokeep the napkin 10 properly positioned in the panty. A preferredattachment means 71 is a pressure-sensitive adhesive, as is well knownin the art. Alternatively, the flaps 70 may be attached to each other onthe underside of the panty by the attachment means 71 without beingaffixed to the panty.

In the preferred embodiment shown, the flaps 70 are comprised oftopsheet 25, tissue 31, and barrier sheet 16. Further, in the embodimentshown, the flaps 70 are unitary with the laminae of the napkin 10. Inother words, the topsheet 25, tissue 31 and barrier sheet 16 simplyextend laterally beyond the core 34 to form the flaps 70. However, theflaps 70 need not be unitary with the napkin 10 but can be separateelements which are affixed to the napkin 10. Further, the flaps 70 canbe comprised of a single substrate or other laminae configurations. Itis recommended, however, that the flaps 70 have a liquid imperviousbarrier sheet 16. The barrier sheet 16 prevents exudates which reach theflaps 70 from soiling the edges of the wearer's panties. Further, it ispreferable that the flaps 70 be provided with an absorbent layer, atleast to a point beyond the edges of the wearer's panties.Theoretically, only a relatively small amount of menses should reach theflaps 70, therefore, only a relatively small amount of absorbentmaterial is desirable in the flaps 70. However, at least some absorbentmaterial is recommended in order to prevent any exudates that reach theflaps 70 from being able to flow further to unprotected areas. Theabsorbent material may be a tissue, such as the tissue 31, or anextension of the absorbent core 34, such as the WATER-LOCK L-535.However, the absorbent material in the flaps 70 should be relativelyhighly flexible. A number of sanitary napkins having flaps suitable oradaptable for use with the sanitary napkins 10 of the present inventionare known. Such flaps are disclosed in U.S. Pat. No. 4,687,478, entitled"Shaped Sanitary Napkin With Flaps", which patent issued to Van Tilburgon Aug. 18, 1987, U.S. Pat. No. 4,608,047, entitled "Sanitary NapkinAttachment Means", which patent issued to Mattingly on Aug. 26, 1986,U.S. Pat. No. 4,589,876, entitled "Sanitary Napkin", which patent issuedto Van Tilburg on May 20, 1986, and U.S. Pat. No. 4,285,343, entitled"Sanitary Napkin", which patent issued to McNair on Aug. 25, 1981, allof which patents are incorporated herein by reference.

For illustration purposes, the central absorbent width 63 of the napkin10 shown in FIG. 4 would extend laterally from the outer edge 32 of thetissue 31 in the one flap 70 to the outer edge 32 of the tissue 31 inthe other flap 70.

Another alternative embodiment of a sanitary napkin 10 of the presentinvention is shown in FIG. 5. Like the napkin 10 shown in FIG. 4, thisnapkin 10 also has flaps 70, only of a different configuration. In thisembodiment, the flaps 70 are comprised only of the topsheet 25 and thebarrier sheet 55.

For illustration purposes, the central absorbent width 63 of the napkin10 shown in FIG. 5 would extend laterally from one outer edge 32 of thetissue 31 to the other outer edge 32 of the tissue 31.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention.

What is claimed is:
 1. A sanitary napkin comprising:a liquid permeabletopsheet; a liquid impermeable barrier sheet; an absorbent coreintermediate said topsheet and said barrier sheet; said sanitary napkinhaving a test capacity of at least 8.0 grams, a total capacity of atleast about 20.0 grams, an absorbent portion with a flexure resistanceless than 250.0 grams, and a caliper less than 2.6 millimeters.
 2. Asanitary napkin according to claim 1 having a total capacity of at least30.0 grams.
 3. A sanitary napkin according to claim 2 having a testcapacity of at least 15.0 grams.
 4. A sanitary napkin according to claim2 having a total capacity of at least 40.0 grams.
 5. A sanitary napkinaccording to claim 4 having a test capacity of at least 18.0 grams.
 6. Asanitary napkin according to claim 1 having a flexure resistance lessthan 175.0 grams.
 7. A sanitary napkin according to claim 6 having aflexure resistance less than 130.0 grams.